Objectives
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1. Describe and explain the three parts
of the cell theory
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2. Determine why cells are so small
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3. Compare and contrast the structure
of Prokaryotic and Eukaryotic Cells
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4. Describe the structure of the cell
membrane
Cell Features
Group Challenge
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What are 5 characteristics of the
cell?
Why are cells so small?
Group Challenge

How are cells made?

What do cells make up?

What protects the cell?
Cell Theory
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Schleiden, Schwann, and Virchow
1. All living things are made of one or
more cells
2. Cells are the basic units of structure
and function
3. All cells arise from existing cells
Common Features of Cells

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Cell Membrane – encloses the cell
and separates the cell interior from
outside the cell. Regulates what
comes in and out of the cell.
Cytoplasm – region of cell within the
membrane that includes the fluid,
cytoskeleton, and all organelles
except the nucleus.
Common Features of Cells

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Cytoskeleton – the cytoplasmic
network of protein filaments that
play a role in cell movement, shape,
and division.
Ribosomes – a cell organelle
composed of RNA and protein
synthesis.
Prokaryotes
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Smallest and simplest cell
Single celled, lacks a nucleus and
other internal compartments
Therefore can’t carry out many
specialized functions
• Example Bacteria
Characteristics of Prokaryotes
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Can Exist in a broad range of
environments
Enzymes and Ribosomes are free to move
around in the cytoplasm.
No internal structures to divide the cell
Single circular molecule of DNA
Have a cell wall that provides structure
and support and made of polysaccharides
Cell wall can be surrounded by a capsule
which enables cell to cling to other objects
Characteristics of Prokaryotes
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Many Prokaryotes have a flagella.
Flagella – a long threadlike structure
that protrude from the cells surface.
What is the function of a flagella
Prokaryotic Cell
Eukaryotic Cells

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The first cells with compartment
Eukaryotic Cells have a nucleus
• Nucleus is an internal compartment that
houses the cells DNA

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• The Eukaryotic Cell has membrane
bound organelles
Eukaryotic cell DNA is organized into
chromosomes
Large Ribosomes
Cytoskeleton

Provides the interior framework of an
animal cell
3 Types of Cytoskeleton Fibers
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Actin Fibers – Play a major role in
determining the shape of animal cells by
pushing and pulling
Microtubules – Act as a highway system
for transportation of information from the
nucleus to different parts of the cell
Intermediate Fibers – Provide a frame on
which the ribosomes and enzymes can be
confirmed to specific regions of the cell.
The Cell Membrane

Cell membranes are not rigid but
fluid
Fluidity is caused by lipids which
form the foundation
Selectively Permeable
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Made of Phospholipids
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Phospholipids
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Lipid made of a phosphate group and
two fatty acids.
Polar Head and Two Non-Polar tails
Phospholipids arranged in a bi-layer